The mechanism of electrodes surface inclusions influence on vacuum insulation characteristics

It is known, that vacuum gap insulation characteristics deteriorate at various types of inclusions on the electrodes surface presence. The greatest influence on the prebreakdown currents and the vacuum gap breakdown voltage are non-metallic inclusions due to the positive charge on them appearance. This charge enhances the surface electric field. There are several hypotheses to explain the vacuum gap conductivity. However, none of them confirmed the existence of such factors as: the presence of several electrons spectrums with energy lower than the Fermi level, changing the emission centres number at temperature exposion, ion irradiation effect and etc. The author suggested to consider the border of inclusions-metal contact as pores type, and to explain the phenomena observed by processes in the pores and supported by these processes Townsend discharge in vacuum gap.